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Biomechanics of spinal trauma
Published in Youlian Hong, Roger Bartlett, Routledge Handbook of Biomechanics and Human Movement Science, 2008
Brian D. Stemper, Narayan Yoganandan
Several ligaments interconnect each vertebral segment. Ligaments are elastic bands made up of collagen and elastin fibres arranged in parallel (Nachemson et al., 1968). Five primary ligaments interconnect each segmental level: anterior and posterior longitudinal ligaments, ligamentum flavum, interspinous ligament, and facet joint capsular ligament. The longitudinal ligaments run continuously along anterior and posterior vertebral body surfaces from cervical to lumbosacral regions. The anterior longitudinal ligament is a broad ligament covering most of the vertebral body anterior surface. The posterior longitudinal ligament is similar to its anterior counterpart, although about one-third as wide. Individual deep fibers of these liagments traverse a single disc and superficial fibers may traverse several segments. The ligamentum flavum, or yellow ligament, spans between adjacent laminae. The thickness of the ligamentum flavum increases inferiorly. The interspinous ligament spans between spinous processes of adjacent levels. The ligamentum flavum and interspinous ligaments are not continuous as fibers connect opposing surfaces of adjacent vertebrae. Capsular ligaments along with synovial membranes and synovial fluid form the facet joints. These synovial joints consist of fluid between the adjacent articular processes. The synovial membrane contains the fluid, and the capsular ligament forms a band around the membrane. The membrane and ligament are collectively known as the joint capsule. Posterior to the spinous processes is the supraspinous ligament in thoracic and lumbar regions and the ligamentum nuchae in the cervical region. The nuchae extends from the occipital bone of the cranium to the posterior extents of cervical spinous processes. The thin supraspinous ligament runs continuously along the posterior extents of spinous processes from C7 to the sacral region.
Prelanding movement strategies among chronic ankle instability, coper, and control subjects
Published in Sports Biomechanics, 2022
Seunguk Han, Seong Jun Son, Hyunsoo Kim, Hyunwook Lee, Matthew Seeley, Ty Hopkins
While CAI patients had greater ankle inversion angle (Delahunt et al., 2007) and decreased dorsiflexion angle (Delahunt et al., 2006) prior to initial contact during drop landing or walking, prior data were limited to uniplanar movement tasks, which were oversimplified relative to actual sporting activities. The current study investigated prelanding movement strategies (e.g., joint kinematics and preactivation of the entire lower extremity) using a more functional and sports-related multiplanar jump landing/cutting task. Contrary to the previous findings, we identified no changes in ankle inversion angle (Figure 2a-2 and −3) while less plantarflexion was observed in CAI patients (Figure 1a-2 and −3). Our data are consistent with the findings of Brown (2011) who reported that copers showed decreased inversion compared to uninjured controls during prelanding. Both CAI and coper groups demonstrated a more ‘closed pack position’ indicating less vulnerable ankle positions to LASs, presumably to reduce the risk of recurrent LASs and/or giving way episodes. CAI patients seem to rely more on alterations in the sagittal plane with an increased ankle dorsiflexion angle to make a less vulnerable position, while copers may rely more on changes in the frontal plane with a lesser ankle inversion angle. It may be postulated that CAI patients rely more on static restraints (e.g., bone and joint capsule) to compensate for the sensorimotor deficits (Hertel & Corbett, 2019) but copers are still able to utilise dynamic restraints of the ankle to maintain joint stability.
A comprehensive and volumetric musculoskeletal model for the dynamic simulation of the shoulder function
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2019
Fabien Péan, Christine Tanner, Christian Gerber, Philipp Fürnstahl, Orcun Goksel
The glenohumeral, acromioclavicular, and sternoclavicular joints were modelled as ball-socket joints with a compliance of 0.1 mm/N (Luis et al. 2007), i.e. as attached to virtual point at the joint center with a spring of 10 N/mm stiffness. The acromioclavicular joint center was determined as the most frontal point of the acromion. The sternoclavicular joint center was positioned at the sternum notch. The glenohumeral joint center was determined as the center of a sphere fitted to the humeral head. The above compliance constraint of the glenohumeral joint models the cartilage and the joint capsule, holding a bone close to its rest location while still allowing for some motion of the humerus head under forces in the neighborhood of the glenohumeral joint center. This prevents a simple dislocation under no force, while active muscle involvement provided by the controller is still required for avoiding dislocation during motion. Note that for the motions presented, no joint-stabilizing constraint or cost term were added explicitly to our controller scheme, although this would be possible in order to accommodate more complex motion paths and to emulate physiological rotator cuff function of joint stabilization.
Evaluation of fixation after plating of distal radius fractures - a validation study
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2021
Takahiro Yamazaki, Yusuke Matsuura, Takane Suzuki, Seiji Ohtori
We used five fresh-frozen cadavers with 10 upper limbs from the Clinical Anatomy Lab in our University. They included two males and three females with a mean age of 88.8 years (range, 68-103 years). The exclusion criteria were obvious trauma or deformity of the wrist joints. The specimens were dissected from the forearm and distally to the midcarpal joint. The attached muscles and neurovascular structures were resected to the extent possible, leaving the bone, joint capsule, ligaments, and interosseous membrane intact. The proximal carpal row and proximal forearm were fixed with resin cement. The first CT scan (Aquilion ONE; Toshiba Medical Systems, Tokyo, Japan, 320-row detector 120 kV, 200 mA, slice thickness 0.5 mm, pixel width 0.3 mm) was performed in this condition.